1. Field of the Invention
The present invention relates to a new actinic ray curable inkjet ink composition, a printed article, a shaped printed product, and a printed article forming method.
2. Description of the Related Art
There are many image-recording methods for forming an image on a recording medium such as paper based on image data signals, including those by an electrophotographic process, a sublimation or fusion heat-transfer process, and an inkjet process. Among them, the inkjet process is advantageous in that it allows printing in a cheaper device, and because it forms an image directly on a recording medium by ejecting ink only in a required image region, and ink can be used efficiently, and a running cost is low.
According to the inkjet method, it is possible to print not only on regular paper but also on a non-absorptive recording medium such as a plastic sheet or a metal plate. However, increased speed at the time of printing and increased image quality are key issues, and it is a property of the inkjet method that the time required for drying and curing droplets after printing greatly affects the productivity of printed materials and the sharpness of printed images.
As one of the inkjet methods, there is a recording method using an inkjet recording ink that is curable by irradiation of radiation. According to this method, by curing ink droplets by irradiating radiation immediately after or after a fixed time after the ink is ejected, the productivity of printing can be increased, and sharp images can be formed.
However, in inkjet printing in which printing is performed in large amounts at high speed, printed recording media are stacked at an outlet in large amounts at high speed. In that case, when curing of printing ink is not sufficient, a phenomenon in which ink is transferred to another printed article in the stack (blocking) may occur. Accordingly, there is demand for inks that cure with higher sensitivity than conventional inks and suppress blocking (inks having favorable sensitivity for preventing blocking).
Meanwhile, when the printed article has insufficient flexibility or stretchability in a subsequent step of processing the same, cracking, white deletion or the like may occur in the obtained image surface during a process in which the printed article is slowly stretched and formed by heating.
Moreover, when the printed article has insufficient impact resistance against a quick impact due to cutting during a subsequent process of punching the printed article into formed products, cracks may be formed at a cut surface of the printed article or in the vicinity thereof. Inferior punching suitability of the printed article may damage its value as a commercial product.
From the viewpoint of producing a film that exhibits favorable adhesiveness, flexibility and strength, Japanese Patent Application Laid-Open (JP-A) No. 2008-37879 proposes an actinic ray curable composition including a photopolymerization initiator, a photopolymerizable compound and rubber fine particles.
From the viewpoint of achieving favorable forming processability, JP-A No. 2008-105393 proposes an ink composition including a monofunctional radical polymerizable monomer having only one unsaturated double bond group, such as a (meth)acrylate group, and at least one group having a cyclic structure.